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The spectroscopy database is not designed to take spectrum images and though digitisation is straightforward using freely available software
Here is a “quick and dirty” digitised spectrum off the jpg of the observation 2026-08-31 compared with one from the same night by Francois Teyssier from the ARAS database at much higher resolution so spline smoothed for this comparison.
For wavelength calibration I used a 4th order polynomial based on 8 identified emission lines and since I did not have a reference star for flux calibration, I rectified (flattened) the spectra.
Apart for the strength of the H alpha line which was saturated in the jpg image, the agreement looks good.Cheers
RobinAttachments:
Hi Mike,
The spectroscopy database is not designed to take spectrum images and though digitisation is straightforward using freely available software, the precise wavelength calibration of objective prism spectra is tricky due to the lack of a reference point and very non linear dispersion. It could still probably be achieved though. Do I remember correctly that you had a previous setup which allows some light from the star to bypass the prism, allowing an image of the star to be produced? This could be used as a reference point for wavelength calibration. If you are interested I could take a look and see what could be done. (The database does allow an image to accompany the digitised spectrum so the original spectrum image could be archived alongside the calibrated digitised version)
Cheers
RobinWith Chrome, I am logged out as soon as I close the tab. I do have an advert and 3rd party cookie’s blocker, though other forums eg Cloudy Nights, Stargazer’s lounge keep me logged in unless I specifically log out
Cheers
Robinmight catch out people who don’t stay logged in all the time, like me.
You can stay logged in ?? How do you do that ? (I have never been able to stay logged in, a source of annoyance)
Cheers
RobinA spectrum taken 20260825.852 showing clear P Cygni profiles at H alpha and H beta. The velocity in H alpha is ~1500km/s confirming its status as a Nova
https://britastro.org/specdb/data_graph.php?obs_id=21386Cheers
RobinThe spectrum has changed dramatically in just a day
The brightness also dropped by a magnitude (AAVSO light curve)
A new feature has appeared between H beta and H gamma. It looks very much like the ‘Bowen fluorescence’ feature seen in cataclysmic variables (plus some He II ?) as it is much broader than the other lines
Yes it is there in my spectrum from last night. (blueward of where HeII would be) The spectrum has changed dramatically in just a day
https://britastro.org/specdb/data_graph.php?obs_id=21380%2C21367&multi=yes&mix_flux=yesCheers
RobinAttachments:
A spectrum from last night. Just managed to get 15 min exposure at culmination (12 deg elevation) in twilight. Impressively broad lines. H alpha FWHM ~3300 km/s
https://britastro.org/specdb/data_graph.php?obs_id=21365Cheers
Robinspectroscopy from other BAA members
Not BAA members (AFAIK) but the 2SPOT team have posted (parts of) an echelle spectrum taken from Chile here
http://www.astrosurf.com/topic/184807-nova-sur-2026c/Cheers
RobinHi Grant,
I think to engage people interested in the science side of astronomy you have to be where the largest numbers who might be interested can be found which is in the astro forums and the profile of the BAA is very low there.
I spend a lot of time out there in various groups engaging with people interested in spectroscopy, promoting spectroscopy, showing examples and helping them. While most of it is in the science sections of general astro groups or special interest groups (If you look at what is going on in the Cloudy Nights Scientific Amateur Astronomy subforum for example, there is some interesting stuff going on there), I also drop in on the “pretty picture” imagers from time to time to give a science view of what is in their images, show them a spectrum, explain why light leaks in their filters is turning the red stars in their narrow band filtered images into planetary nebulae etc which generates quite a bit of interest. As part of that I also try to raise the profile of the BAA where I can, linking to the gallery, video talks, spectra in the BAA database, section content etc which at least brings them to the BAA website. Jeremy is on Stargazers Lounge and there are a couple of others but generally I don’t often see other BAA members.
Concerning AI, it can only find the good stuff if it is out there. In Cloudy Nights there is someone building an impressive “point an click” application which can take an image full of slitless spectra taken using a Star Analyser and identify objects in it, generate fully calibrated spectra and roughly classify them. He is using AI a lot and commented that most of the queries about using the Star Analyser lead back to stuff I put out there.
Much better result showing hydrogen emission lines (and a hint of Fe lines?)
That is interesting. Unlike the spectra in the ATel and your latest spectrum, my spectrum from 20260813.103 definitely shows no net emission except for the H alpha P Cygni. (I’ve double checked everything and there is no obvious issue with the result so it looks like it has gone from emission to absorption and back to emission in a few days.
Cheers
RobinA spectrum from this morning. (ALPY 600 ~12A resolution)
https://britastro.org/specdb/data_graph.php?obs_id=21286
Quite a change from the one posted in the ATel. Except for a narrow PCygni profiled H alpha, all other lines are in net absorption currently. It is also significantly red, (the one in the ATel had been rectified)Cheers
RobinWe’ve been here before though. I was looking around for more information and started reading an article in the Times on it, everything was the same but some of the names were wrong. I then noticed the article was headed March 2008 !
The annual cost back then was £2.5m so I would say £2.8M today is pretty good cost control.
Call me a sceptic but I reckon it will suddenly be “saved” and the public will forget about it. meanwhile the arguably perhaps even more damaging cuts will be applied elsewhere in UK astronomy and particle physics. We can perhaps hope though that this might prompt a debate about Britain’s role in maintaining some credibility in science in the west given what is going on the the US
Cheers
Robinand Jodrell Bank is just the exposed tip of a large iceberg
from the BBC
“The UK will no longer participate in research at the James Clark Maxwell Telescope in Hawaii, which scientists are using to image supermassive black holes at the centre of galaxies.
UKRI has also cut funding for the UK’s involvement in two instruments on the Extremely Large Telescope which is being built in Chile to search for signs of life on other Earth-like worlds.”
An earlier piece also mentioned cutting Vera Rubin involvement
My Sloan photometry shows that it is currently getting redder as it fades. I assume that this is due to the current dominant H-alpha emission.
I don’t have the Sloan passbands in a digitised form to hand but H alpha emission currently accounts for approximately 40% of the flux in the Bessell R passband
EDIT: About 50% in Sloan r’
Cheers
RobinAttachments:
Spectra by me and David Boyd last night (in the BAA database)
Cheers
RobinAttachments:
The nice thing with the individual measurements (both in photometry and spectroscopy) is you can use them to make a true estimate of the stochastic uncertainty (though not any systematic errors)
A quick spectrum last night with the very low resolution ALPY200 to cover the IR, though it would be bright enough to record spectra at higher resolution particularly for observers with IR capability. Lots of IS extinction and strong H alpha and other emission lines into the IR
https://britastro.org/specdb/data_graph.php?obs_id=20943Cheers
RobinAttachments:
Hi Hugh,
It is complicated by the fact that the hot continuum spectrum of the accreting material is superimposed on the cool star spectrum but I have seen signs that the best fit cool star spectral type once the hot component continuum is removed may vary from M3III in high activity to M4III in low activity based on TiO band depths. See attached slides. (Here I was removing the cool star component to try to see the underlying spectrum of the accreting material)
Cheers
RobinAttachments:
